Effect of Arsenic (III) on the Denitrification Process

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A sequencing batch reactor (SBR) was operated to
develop denitrifying bacteria that had a mean specific
denitrification rate of 0.11 g NO₃⁻-N/gVSS/day.
Another system (an anaerobic digester) was operated
to generate volatile fatty acids (VFAs) with the
effluent concentration being measured to be 5655 ±
876 mg/L as acetic acid. Using the denitrifying
biomass developed in the SBR and VFAs generated in
the digester as an external carbon source, a series of
denitrification batch tests were conducted. The
denitrification batch reactors were spiked with NO₃⁻-
N (to get a C:N ratio of 3.0) and different arsenite
concentrations to quantify the effect of arsenite on the
denitrification rate. A steady deterioration in the
ability of the biomass to denitrify under increasing
arsenite concentrations was observed, with the mean
specific denitrification rate dropping from 0.183 g
NO₃⁻-N/gVSS/day at an arsenite concentration of 5
mg/L, to 0.047 g NO₃⁻-N/gVSS/day at a concentration
of 25 mg/L.

Subjects

denitrification

arsenic

volatile fatty acids

sequencing batch reactor

Fields of Research::290000 Engineering and Technology::290800 Civil Engineering::290802 Water and sanitary engineering